1. Field of the Invention
The present invention generally relates to a system that allows voice communications over a LAN network and, more particularly, to a wireless trunk that enables voice over LAN communications outside the LAN network by way of a wireless interface formed from a standard wireless telephone, such as a cellular telephone, and an adapter.
2. Description of the Prior Art
Packet based communications networks have been in use for many years. However, a relatively new feature in such networks is telephony over local area network (LAN) systems. In particular, a network user is able to pick up a telephone connected to the LAN and complete a call to a destination user who is connected to either the same or a different network server, without using the public switched telephone network. This is accomplished by converting voice received from the telephone handset into packet data and sending the packets over the local area network to the destination caller. The packet data is then converted back into voice at the destination such that a user may listen on a telephone handset.
Currently, in order to place a call to a telephone user not connected to the network, the call is automatically routed to a public switched telephone network from where the call is completed to the destination telephone. This requires the network to be hardwired to a land-line based external trunk which is routed through a telephone company central office. Use of external hardwired trunks is known to have several drawbacks including the requirement that land-lines be available even in remote areas. Also, in emergency situations, when a land-line based trunk fails, or there is a failure in the public network, callers may be unable to dial out from the network. Thus, there is a need for a wireless trunk for use with telephony over LAN networks.
Briefly, the present invention relates to a system that enables voice over LAN communications outside a LAN telephone network to be accomplished by way of a wireless interface formed from a standard wireless telephone, such as a cellular telephone, and an adapter. The adapter is configured to interface the wireless telephone to the communication network, such that the wireless telephone may be used as the wireless trunk. In operation, a network based user initiates a call intended for someone outside the network and the call is routed to its destination over the wireless telephone network, via the wireless telephone. The network and the adapter communicate with each other using standard network signaling protocols. Likewise, the adapter and the wireless telephone communicate with each other using known cellular signaling protocols. The adapter functions as a protocol converter or translator to translate between the network signalling and wireless telephone signalling commands.
In accordance with one aspect of the invention, the adapter enables seamless communication between the network, such as a LAN, and a wireless communications network via the wireless telephone. As such, the wireless telephone provides wireless trunk capabilities to telephone calls that originate on the LAN but are destined for recipients not connected to it. In a particular embodiment of the invention, the adapter, which is interfaced to the LAN, is placed in a housing constructed such that a connector on the adapter automatically plugs into an interface connector in the wireless telephone when the telephone is inserted into the adapter. The adapter, through the interface connector, is then able to translate signals between the cellular telephone and the LAN such that the voice may be transferred from the LAN to the cellular telephone network and vice versa. In another embodiment of the invention, the adapter is housed in a standalone enclosure that may be wired in-between the wireless telephone and an interface for the LAN.